1. Field of the Invention
The present invention relates to an ultrasonic probe apparatus, and more particularly to an ultrasonic probe apparatus which can hold an ultrasonic transducer assembly (hereinafter, referred to as "ultrasonic probe") having a phased array transducer in tight contact with a surface of an object to be examined.
2. Description of the Prior Art
In an ultrasonic diagnostic apparatus, ultrasonic waves are emitted from an ultrasonic transducer provided in an ultrasonic probe into an object to be examined. The echoes reflected from various parts of different acoustic impedances are received by the transducer, and data based on the received echoes are displayed on a cathode ray tube (CRT) as a visual image. In the ultrasonic diagnostic apparatus thus constructed, it is possible to observe properties of biological tissues of the object to be examined by displaying the obtained echo data as various tomographic images or by representing the echo data as dynamic curves (e.g. ultrasonic cardiograms).
In the conventional way of observing a tomographic image of a required region of a living body to be examined by means of the ultrasonic diagnostic apparatus, first an operator holds the ultrasonic probe with his hand, and then brings the transducer thereof into contact with the surface of the required region of the living body to be examined. Thereafter, the operator adjusts the contact angle and contact position of the probe with respect to the body surface appropriately, while observing the displayed image, in order to obtain a required ultrasonic tomographic image, for instance.
In recent years, an ultrasonic diagnostic method so called as stress echocardiography testing has been widely used. The stress echocardiography testing diagnoses a person to be examined through a B mode ultrasonic tomographic image under the condition that heart rate of the person is compellingly or forcibly increased by applying a load thereto. According to the stress echocardiography testing, it is possible to observe cardiac function of a person to be examined which can not be observed under the condition that the person is lying quiet in bed, which is advantageous in finding an early stage of a heart disease such as ischemic heart disease (IHD).
As the methods performing the stress echocardiography testing, there are known some methods. In these methods, there is a method in which medicine or electrical shock is given to a person to be examined in order to compellingly increase its heart rate. However, this method has problems due to less safety for the examined person or increased burden of the examined person. For these reasons, there is widely used a method in which a person to be examined is exercised under the natural condition by using a treadmill or the like to increase its heart rate compellingly and cardiac function of the heart of the person under that condition is observed through B mode ultrasonic tomographic image.
The above method is preferable in view of the safety and reduced burden of the examined person. However, in this method, a diagnosis has to be performed under the condition that the examined person is walking or running on the treadmill with standing posture, which is quite different from the condition that the person is lying quiet in bed. Further, in the stress echocardiography testing, it is required to obtain data on the same part of the examined person for several times over a relatively long time, for example at three minutes after, five minutes after and ten minutes after.
Therefore, in the stress echocardiography testing, is required to accurately maintain the probe for a long time at a predetermined position on the body surface of the examined person who is walking or running with standing posture. Therefore, in the conventional method, two operators are required to attend the stress echocardiography testing, in which one of the operators holds the probe with his hand on the body surface of the examined person and the other operator manipulates and monitors the diagnostic apparatus.
However, the prior art method is not economical because two operators are required to attend the diagnosis. Further, it is difficult to obtain an accurate B mode ultrasonic tomographic image by merely holding the ultrasonic probe with the hand of the operator since the scanning plane is likely to be dislocated during the diagnosis by the vibration from the examined person. For these reasons, it has been desired to develop an apparatus which is suitable for use in the stress echocardiography testing, that is an apparatus which can hold the ultrasonic probe stably on the body surface of the examined person for a long time during the stress echocardiography testing.
As such an apparatus that can hold an ultrasonic probe onto a body surface of the examined person, there is known one which is disclosed in Japanese Utility Model Publication No. 58-6405.
FIGS. 1 and 2 show the ultrasonic probe apparatus disclosed in this Utility Model Publication. The apparatus comprises a roughly cylindrical ultrasonic probe 12 provided with a single element ultrasonic transducer 10 for emitting and receiving an ultrasonic beam, and a supporting member 18 for supporting the ultrasonic probe 12 so as to be pivotable and inclinable.
Further, a cable 14 is connected to the ultrasonic probe 12, in order to transmit a signal for exciting the ultrasonic transducer 10 from a control section off an ultrasonic diagnostic apparatus (not shown) to the transducer 10 and feed an echo signal based on the echo received by the ultrasonic transducer 10 to the control section of the diagnostic apparatus. Further, a male connector 16 to be coupled to a female connector (not shown) of the control section of the ultrasonic diagnostic apparatus is attached to a free end of the cable 14.
The supporting member 18 includes a first holder 20 for supporting the ultrasonic probe 12 therewithin and a second holder 22 for supporting the first holder 20 which supports the probe 12 so as to be pivotable and inclinable with respect to the second holder 22.
The first holder 20 is formed into a roughly semi-spherical shape having an inner space into which the ultrasonic transducer assembly 12 can be fitted. The cable 14 extends from the top of the first holder 20. The ultrasonic probe 12 fitted into the inner space of the first holder 20 is adjustably pivoted and then fixed therein with a locking screw 34. Further, when this locking screw 34 is loosened, the ultrasonic probe 12 can be removed from the first holder 20 so as to be usable for the ordinary ultrasonic diagnosis.
The second holder 22 is provided with a cylindrical portion 22a having an opening to which the first holder 20 can be fitted. The inner circumferential surface of this cylindrical portion 22a is formed into a semi-spherical surface which defines a pivotal holding portion 26, to which a semi-spherical pivotal portion 28 defined by an outer spherical circumferential surface of the first holder 20 is pivotally fitted. Accordingly, the ultrasonic probe 12 can be held pivotally relative to the second holder 22 of the supporting member 18 through the first holder 20.
Further, a slit 30 is formed at a part of the cylindrical portion 22a of the second holder 22, so as to extend radially to the inner opening thereof in the horizontal direction perpendicular to the axial direction of the cylindrical portion 22a. A threaded hole is formed at the part of the cylindrical portion 22a in which the slit 30 is formed, so as to pass through The slit 30 in the axial direction of the cylindrical portion 22a. Into this threaded hole, a locking screw 32 is screwed, so that both the holders 20 and 22 can be fixed with respect to each other when the locking screw 32 is fastened.
The second holder 22 is formed integrally with three holding legs 24a, 24b and 24c. These legs 24a, 24b and 24c are formed of a relatively hard material and extend radially outward in the direction perpendicular to the axial direction of the cylindrical portion 22a at regular angular intervals. Therefore, the ultrasonic probe 12 can be held onto a body surface of a person to be examined in such a manner that the transducer 10 is brought into contact with the body surface, when these legs 24a, 24b and 24c are attached onto the body surface by use of an adhesive tape, for instance.
In use of this prior art ultrasonic probe apparatus constructed as described above, first the ultrasonic probe 12 is mounted within the first holder 20 with a locking screw 34. Thereafter, the first holder 20 with the probe 12 is mounted to the second holder 22 by means of the locking screw 32. Further, the three holding legs 24a, 24b and 24c are attached onto the body surface of the person to be examined with an adhesive tape in such a manner that the ultrasonic transducer 10 is brought into tight contact with the body surface. Under these conditions, an ultrasonic beam is emitted from the ultrasonic transducer 10 arranged inside the ultrasonic probe 12 toward a required biological tissue to be examined through the body surface, and the echo reflected from the biological tissue is received by the transducer 10.
This prior art ultrasonic probe apparatus has been developed mainly for use in ultrasonic cardiography testing for a person to be examined who is lying quiet, in bed. However, if this prior art ultrasonic probe apparatus would be applied to stress echocardiography testing, it is supposed that the desire described above that holds the ultrasonic probe onto the body surface of the examined person for a long time during the stress echocardiography testing may be satisfied.
However, in this prior art ultrasonic probe apparatus, since the holding legs 24a, 24b and 24c integrally formed with the second holder 22 do not have flexibility, there is a case that these legs 24a, 24b and 24c are not sufficiently attached to the body surface due to the difference in a figure of a body of individual person to be examined. In particular, during the stress echocardiography testing, the examined person is sometimes imposed to have unnatural posture in which a body surface thereof is deformed.
Further, in diagnosis for ischemic heart disease (IHD), it is necessary to obtain a tomographic image of a heart along a minor axis direction thereof. In obtaining such a tomographic image, the ultrasonic probe apparatus has to be attached onto a body surface of a person to be examined at a position just below the left ribs thereof such that the beam from the transducer is directed upwardly. However, there are many unevenness such as ribs or breast around that position. Therefore, it is difficult to attach and hold the prior art ultrasonic transducer apparatus on that position appropriately and stably.
For these reasons, the prior art ultrasonic probe apparatus can not be used in the stress echocardiography testing as it is.
Furthermore, during the stress echocardiography testing, there is a case that different regions of the heart are required to be diagnosed, or that the scanning plane by the transducer is dislocated due to the motion or the vibration of the examined person. Therefore, in the ultrasonic transducer apparatus for the stress echocardiography testing, it is preferable that the ultrasonic wave emitting direction can be adjusted under the fixed condition by modifying or correcting the contact angle and contact position of the ultrasonic probe relative to the examined person, if necessary. In addition, in order to obtain a preferable B mode tomographic image, it is necessary to adjust the ultrasonic wave emitting direction appropriately under the fixed condition. However, it is difficult to satisfy these necessities by merely applying the prior art ultrasonic transducer apparatus to the stress echocardiography testing.